Method of manufacturing a fluid-filled chamber with a reinforcing element

ABSTRACT

Several sole components and a method of manufacturing those sole components are disclosed. In general, each sole component includes a fluid-filled bladder and a reinforcing element extending around a portion of the bladder. The reinforcing element is bonded to the exterior of the bladder, and may be recessed into the bladder. In some configurations, the reinforcing element is die-cut from a sheet of polymer material, and the reinforcing element may exhibit a layered configuration. In manufacturing the sole component, the reinforcing element may be located within a mold, and the polymer material forming the bladder may be bonded to the reinforcing element during the molding process.

CROSS-REFERENCE To RELATED APPLICATIONS

This non-provisional U.S. patent application is a divisional applicationand claims priority to U.S. patent application Ser. No. 12/014,974,which was filed in the U.S. Patent and Trademark Office on Jan. 16, 2008and entitled “Fluid-Filled Chamber With A Reinforcing Element,” suchprior U.S. patent application being entirely incorporated herein byreference.

BACKGROUND

A conventional article of athletic footwear includes two primaryelements, an upper and a sole structure. The upper may be formed from aplurality of material elements (e.g., textiles, leather, and foammaterials) defining a void that securely receives and positions the footwith respect to the sole structure. The sole structure is secured to alower surface of the upper and is generally positioned to extend betweenthe foot and the ground. In addition to attenuating ground reactionforces, the sole structure may provide traction and control various footmotions, such as pronation. Accordingly, the upper and the solestructure operate cooperatively to provide a comfortable structure thatis suited for a wide variety of ambulatory activities, such as walkingand running.

The sole structure of an article of athletic footwear generally exhibitsa layered configuration that includes a comfort-enhancing insole, aresilient midsole formed from polymer foam, and a ground-contactingoutsole that provides both abrasion-resistance and traction. Suitablepolymer foam materials for the midsole include ethylvinylacetate orpolyurethane that compress resiliently under an applied load toattenuate ground reaction forces. Conventional polymer foam materialscompress resiliently, in part, due to the inclusion of a plurality ofopen or closed cells that define an inner volume substantially displacedby gas. Following repeated compressions, the cell structure of thepolymer foam may deteriorate, thereby resulting in an decreasedcompressibility and decreased force attenuation characteristics of thesole structure.

One manner of reducing the mass of a polymer foam midsole and decreasingthe effects of deterioration following repeated compressions isdisclosed in U.S. Pat. No. 4,183,156 to Rudy, in which cushioning isprovided by a fluid-filled chamber formed of an elastomeric material.The chamber includes a plurality of subchambers that are in fluidcommunication and jointly extend along a length and across a width ofthe footwear. The chamber may be encapsulated in a polymer foammaterial, as disclosed in U.S. Pat. No. 4,219,945 to Rudy. Thecombination of the chamber and the encapsulating polymer foam materialfunctions as a midsole. Accordingly, the upper is attached to the uppersurface of the polymer foam material and an outsole is affixed to thelower surface.

Fluid-filled chambers suitable for footwear applications may bemanufactured by a two-film technique, in which two separate sheets ofelastomeric film are formed to exhibit the overall peripheral shape ofthe chamber. The sheets are then bonded together along their respectiveperipheries to form a sealed structure, and the sheets are also bondedtogether at predetermined interior areas to give the chamber a desiredconfiguration. That is, interior bonds (i.e., bonds spaced inward fromthe periphery) provide the chamber with a predetermined shape and sizeupon pressurization. In order to pressurize the chamber, a nozzle orneedle connected to a fluid pressure source is inserted into a fillinlet formed in the chamber. Following pressurization of the chamber,the fill inlet is sealed and the nozzle is removed. A similar procedure,referred to as thermoforming, may also be utilized, in which a heatedmold forms or otherwise shapes the sheets of elastomeric film during themanufacturing process.

Chambers may also be manufactured by a blow-molding technique, wherein amolten or otherwise softened elastomeric material in the shape of a tubeis placed in a mold having the desired overall shape and configurationof the chamber. The mold has an opening at one location through whichpressurized air is provided. The pressurized air induces the liquefiedelastomeric material to conform to the shape of the inner surfaces ofthe mold. The elastomeric material then cools, thereby forming a chamberwith the desired shape and configuration. As with the two-filmtechnique, a nozzle or needle connected to a fluid pressure source isinserted into a fill inlet formed in the chamber in order to pressurizethe chamber. Following pressurization of the chamber, the fill inlet issealed and the nozzle is removed.

SUMMARY

An article of footwear having an upper and a sole structure isdisclosed. The sole structure includes a chamber and a reinforcingelement. The chamber encloses a fluid, and at least a portion of anexterior surface of the chamber may be formed from a first polymermaterial. The reinforcing element has a first surface and an oppositesecond surface. The first surface may be at least partially formed fromthe first polymer material and bonded to the exterior surface of thechamber. The second surface is at least partially formed from a secondpolymer material, the first polymer material being different than thesecond polymer material.

A method of manufacturing a sole structure for an article of footwear isalso disclosed. The method includes die-cutting a reinforcing elementfrom a planar sheet of polymer material, the reinforcing element havinga first surface and an opposite second surface. The reinforcing elementis located within a mold such that the second surface contacts a surfaceof the mold. The chamber may also be shaped by drawing a polymermaterial against the surface of the mold and against the first surfaceof the reinforcing element.

The advantages and features of novelty characterizing aspects of theinvention are pointed out with particularity in the appended claims. Togain an improved understanding of the advantages and features ofnovelty, however, reference may be made to the following descriptivematter and accompanying drawings that describe and illustrate variousconfigurations and concepts related to the invention.

DESCRIPTION OF THE DRAWINGS

The foregoing Summary and the following Detailed Description will bebetter understood when read in conjunction with the accompanyingdrawings.

FIG. 1 is a lateral side elevational view of the article of footwearincorporating a sole component.

FIG. 2 is a perspective view of the sole component.

FIG. 3 is an exploded perspective view of the sole component.

FIG. 4 is a top plan view of the sole component.

FIG. 5 is a lateral side elevational view of the sole component.

FIG. 6 is a medial side elevational view of the sole component.

FIGS. 7A-7C are cross-sectional views of the sole component, as definedby section lines 7A-7C in FIG. 4.

FIGS. 8A-8C are schematic perspective views depicting a method offorming a reinforcing element of the sole component.

FIGS. 9A and 9B are plan views of portions of a mold for manufacturingthe sole component.

FIGS. 10A-10D are side elevational views depicting a method ofmanufacturing the sole component with the mold.

FIG. 11 is a perspective view of the sole component following removalfrom the mold.

FIGS. 12A-12F are cross-sectional views corresponding with FIG. 7A anddepicting additional configurations of the sole component.

FIGS. 13A-13J are perspective views depicting additional configurationsof the sole component.

FIG. 14 is a cross-sectional view corresponding with FIG. 7A anddepicting an additional configuration of the sole component.

DETAILED DESCRIPTION

The following discussion and accompanying figures disclose various solecomponent configurations suitable for footwear applications. Inaddition, methods of manufacturing the sole components are disclosed.Concepts related to the sole components and manufacturing methods aredisclosed with reference to an article of footwear having aconfiguration that is suitable for running. The sole components are notlimited solely to footwear designed for running, and may be applied to awide range of athletic footwear styles, including basketball shoes,cross-training shoes, walking shoes, tennis shoes, soccer shoes, andhiking boots, for example. The sole component may also be applied tofootwear styles that are generally considered to be non-athletic,including dress shoes, loafers, sandals, and work boots. The conceptsdisclosed herein apply, therefore, to a wide variety of footwear styles.

An article of footwear 10 is depicted in FIG. 1 as including an upper 11and a sole structure 12. Upper 11 may incorporate a plurality ofmaterial elements (e.g., textiles, foam, and leather) that are stitchedor adhesively bonded together to form an interior void for securely andcomfortably receiving a foot. The material elements may be selected andlocated with respect to upper 11 in order to selectively impartproperties of durability, air-permeability, wear-resistance,flexibility, and comfort, for example. In addition, upper 11 may includea lace that is utilized in a conventional manner to modify thedimensions of the interior void, thereby securing the foot within theinterior void and facilitating entry and removal of the foot from theinterior void. The lace may extend through apertures in upper 11, and atongue portion of upper 11 may extend between the interior void and thelace. Accordingly, upper 11 may have a substantially conventionalconfiguration.

Sole structure 12 is secured to upper 11 and includes a midsole 13 andan outsole 14. A conventional midsole may be primarily formed of apolymer foam material, such as polyurethane or ethylvinylacetate, asdiscussed in the Background section. In contrast with the structure ofthe conventional midsole, midsole 13 incorporates a sole component 20,as depicted in FIGS. 2-7C, that includes a fluid-filled bladder 30 andan external reinforcing element 40. Sole component 20 provides groundreaction force attenuation (i.e., cushioning) as footwear 10 impacts theground during running, walking, or other ambulatory activities. Inaddition, sole component 20 may impart stability or otherwise controlfoot motions, such as the degree of pronation. Outsole 14 is secured toa lower surface of midsole 13 and is formed of a durable, wear-resistantmaterial suitable for engaging the ground. Sole structure 12 may alsoinclude an insole with the configuration of a thin cushioning memberthat is positioned within the interior void formed by upper 11 andlocated to contact a plantar surface of the foot, thereby enhancing theoverall comfort of footwear 10.

The following discussion references various general regions of footwear110, upper 11, and sole structure 12 based upon their relativelocations. For reference purposes, footwear 10 may be divided into threegeneral regions: a forefoot region 15, a midfoot region 16, and a heelregion 17, as depicted in FIG. 1. Forefoot region 15 generally includesportions of footwear 10 corresponding with the toes and the jointsconnecting the metatarsals with the phalanges. Midfoot region 16generally includes portions of footwear 10 corresponding with the archarea of the foot, and heel region 17 corresponds with rear portions ofthe foot, including the calcaneus bone. Regions 15-17 are not intendedto demarcate precise areas of footwear 10. Rather, regions 15-17 areintended to represent general areas of footwear 10 to aid in thefollowing discussion. In addition to footwear 10, regions 15-17 may alsobe applied to upper 11, sole structure 12, and individual elementsthereof.

Sole Component Structure

Sole component 20 includes an upper surface 21 and an opposite lowersurface 22. Upper surface 21 is secured to upper 11 in a conventionalmanner, such as adhesive bonding, and may be contoured to conform to theshape of the plantar surface of the foot. Accordingly, upper surface 21may exhibit an elevation in heel region 17 that is greater than anelevation in forefoot region 15, with midfoot region 16 forming atransition between the elevations. Differences in the overall thicknessof sole component 20 may account for the elevation in heel region 17that is greater than the elevation in forefoot region 15. The overallshape of sole component 20, as depicted in the plan view of FIG. 4,corresponds with a shape of a foot. Accordingly, a width of heel region17 may be less than a width of forefoot region 15 to accommodate thevarying width dimensions of the foot. Outsole 14 is also secured tolower surface 22 in a conventional manner, such as adhesive bonding. Inaddition to upper surface 21 and lower surface 22, sole component 20includes a lateral side surface 23 and an opposite medial side surface24. Both side surfaces 23 and 24 are exposed portions of midsole 13 andhave a tapered configuration from heel region 17 to forefoot region 15that facilitates the difference in elevation between heel region 17 andforefoot region 15.

The primary elements of sole component 20 are a fluid-filled bladder 30and an external reinforcing element 40. Bladder 30 is formed from anupper barrier layer 31 and a lower barrier layer 32 that aresubstantially impermeable to a pressurized fluid contained by bladder30. Upper barrier layer 31 and lower barrier layer 32 are bondedtogether around their respective peripheries to form a peripheral bond33 and cooperatively form a sealed chamber, in which the pressurizedfluid is located. The pressurized fluid contained by bladder 30 inducesan outward force upon barrier layers 31 and 32 that tends press outwardupon barrier layers 31 and 32, thereby distending barrier layers 31 and32. In order to restrict the degree of outwardly-directed swelling(i.e., distension) of barrier layers 31 and 32 due to the outward forceof the pressurized fluid, a plurality of interior bonds 34 are formedbetween barrier layers 31 and 32. Interior bonds 34 are spaced inwardfrom side surfaces 23 and 24, and interior bonds 34 are distributedthroughout sole component 20. In the absence of interior bonds 34, theoutward force induced by the pressurized fluid would impart a rounded orotherwise bulging configuration to bladder 30, particularly in areascorresponding with upper surface 21 and lower surface 22. Interior bonds34, however, restrict the degree of the outwardly-directed swelling ordistension of barrier layers 31 and 32 and retain the intended contoursof upper surface 21 and lower surface 22.

Interior bonds 34 may exhibit a variety of configurations. In heelregion 17, the indentations formed by interior bonds 34 have a greaterdepth than in forefoot region 15 due to the increased overall thicknessof sole component 20 in heel region 17. In addition, the area of eachinterior bond 34 in heel region 17 is generally greater than the area ofeach interior bond 34 in forefoot region 15. The position of interiorbonds 34 with respect to upper surface 21 and lower surface 22 may alsovary. For example, interior bonds 34 may be positioned so as to becloser to upper surface 21, midway between surfaces 21 and 22, or at aposition that is closer to lower surface 22. Although interior bonds 34are depicted as being generally horizontal in FIGS. 7A-7C, interiorbonds 34 may also be inclined in some configurations of sole component20.

During running or walking, sole component 20 generally flexes orotherwise bends to accommodate the natural flexing of the foot,particularly in forefoot region 15. In order to facilitate the flexingof sole component 20, a pair of flexion indentations 35 are formed inbladder 30. Each flexion indentation 35 extends laterally across a lowerportion of bladder 30. That is, flexion indentations 35 extend betweenside surfaces 23 and 24, and flexion indentations 35 are formed in lowersurface 22. The location of flexion indentations 35 is also selectedbased upon the average location of the joints between the metatarsalsand the proximal phalanges of the foot. More particularly, flexionindentations 35 are spaced such that one flexion indentation 35 islocated forward of the joints between the metatarsals and the proximalphalanges and the other flexion indentation 35 is located behind thejoints between the metatarsals and the proximal phalanges. The specificlocations of flexion indentations 35 may be selected, for example, to bethree standard deviations away from the average position of the jointsbetween the metatarsals and the proximal phalanges, as determinedthrough statistical anatomical data. Depending upon the specificconfiguration and intended use of sole component 20, however, thelocation of flexion indentations 35 may vary significantly from thepositions discussed above.

Flexion indentations 35 extend laterally (i.e., between side surfaces 23and 24) across lower surface 22. Although this configuration is suitablefor footwear structured for running and a variety of other athleticactivities, flexion indentations 35 may extend in a generallylongitudinal direction (i.e., between forefoot region 15 and heel region17) in footwear structured for athletic activities such as basketball,tennis, or cross-training. Accordingly, flexion indentations 35 mayextend in a variety of directions in order to provide a defined line offlexion in sole component 20. The figures also depict flexionindentations 35 as extending entirely across bladder 30. In someconfigurations, however, flexion indentations 35 may extend onlypartially across bladder 30.

Flexion indentations 35 define portions of sole component 20 that have areduced thickness. Given that the degree of force necessary to bend anobject is at least partially dependent upon the thickness of the object,the reduced thickness of sole component 20 in the areas of flexionindentations 35 facilitates flexing. In addition, portions of outsole 14may extend into flexion indentations 35, thereby forming stiffer, lesscompressible areas of sole structure 12 that also facilitate flexingabout flexion indentations 35.

Flexion indentations 35 form an indentation in lower surface 22 thatcorresponds with the locations of various interior bonds 34. Referringto FIG. 7C, a cross-section through one of flexion indentations 35 isdepicted. With respect to this area, interior bonds 34 extend downwardto bond upper barrier layer 31 with the portion of lower barrier layer32 that defines the flexion indentation 35. Some prior art bladdersincorporate bonds that form flexion points, and the flexion points mayform relatively hard areas due to the lack of a fluid cushion in thearea of the flexion points. That is, the flexion points generally formnon-cushioning areas of the prior art bladders. In contrast with theprior art flexion points, a space is formed between flexion indentations35 and upper barrier layer 31 that includes the fluid such that flexionindentations 35 provide an advantage of simultaneously accommodatingflexing and providing ground reaction force attenuation. As analternative, no interior bonds 34 may be formed in areas that defineflexion indentations 35.

A variety of thermoplastic polymer materials may be utilized for bladder30, and particularly barrier layers 31 and 32, including polyurethane,polyester, polyester polyurethane, and polyether polyurethane. Anothersuitable material for bladder 30 is a film formed from alternatinglayers of thermoplastic polyurethane and ethylene-vinyl alcoholcopolymer, as disclosed in U.S. Pat. Nos. 5,713,141 and 5,952,065 toMitchell et al, incorporated herein by reference. A variation upon thismaterial wherein the center layer is formed of ethylene-vinyl alcoholcopolymer; the two layers adjacent to the center layer are formed ofthermoplastic polyurethane; and the outer layers are formed of a regrindmaterial of thermoplastic polyurethane and ethylene-vinyl alcoholcopolymer may also be utilized. Bladder 30 may also be formed from aflexible microlayer membrane that includes alternating layers of a gasbarrier material and an elastomeric material, as disclosed in U.S. Pat.Nos. 6,082,025 and 6,127,026 to Bonk et al., both incorporated herein byreference. In addition, numerous thermoplastic urethanes may beutilized, such as PELLETHANE, a product of the Dow Chemical Company;ELASTOLLAN, a product of the BASF Corporation; and ESTANE, a product ofthe B.F. Goodrich Company, all of which are either ester or ether based.Still other thermoplastic urethanes based on polyesters, polyethers,polycaprolactone, and polycarbonate macrogels may be employed, andvarious nitrogen blocking materials may also be utilized. Additionalsuitable materials are disclosed in U.S. Pat. Nos. 4,183,156 and4,219,945 to Rudy, incorporated herein by reference. Further suitablematerials include thermoplastic films containing a crystalline material,as disclosed in U.S. Pat. Nos. 4,936,029 and 5,042,176 to Rudy,incorporated herein by reference, and polyurethane including a polyesterpolyol, as disclosed in U.S. Pat. Nos. 6,013,340; 6,203,868; and6,321,465 to Bonk et al., also incorporated herein by reference.

The fluid within bladder 30 may be any of the gasses disclosed in U.S.Pat. No. 4,340,626 to Rudy, incorporated herein by reference, such ashexafluoroethane and sulfur hexafluoride, for example. The fluid mayalso include gasses such as pressurized octafluorapropane, nitrogen, orair. In addition to gasses, various gels or liquids may be sealed withinbladder 30. Accordingly, a variety of fluids are suitable for bladder30. With regard to pressure, a suitable fluid pressure is fifteen poundsper square inch, but may range from zero to thirty pounds per squareinch. Accordingly, the fluid pressure within bladder 30 may berelatively high, or the fluid pressure may be at ambient pressure or ata pressure that is slightly elevated from ambient in someconfigurations.

Interior bonds 34, as discussed above, are spaced inward from sidesurfaces 23 and 24 to restrict the degree of outwardly-directed swelling(i.e., distension) of barrier layers 31 and 32, particularly in areascorresponding with upper surface 21 and lower surface 22. Interior bonds34 may not, however, significantly restrict the outwardly-directedswelling of side surfaces 23 and 24. One purpose of reinforcing element40 is, therefore, to restrict the degree of outwardly-directed swellingin side surfaces 23 and 24, thereby retaining the intended overall shapeof sole component 20.

Reinforcing element 40 includes an upper portion 41, a lower portion 42,and a plurality of connecting portions 43. When incorporated into solecomponent 20, reinforcing element 40 exhibits a generally U-shapedconfiguration. Upper portion 41 is positioned at the interface of uppersurface 21 and side surfaces 23 and 24. Accordingly, upper portion 41extends along lateral side 23 from midfoot region 16 to heel region 17,extends around heel region 17, and also extends along medial side 24from midfoot region 16 to heel region 17. Lower portion 42 is positionedat the interface of lower surface 22 and side surfaces 23 and 24. Lowerportion 42 extends through heel region 17 and may extend into rearwardportions of midfoot region 16. Connecting portions 43 extend along sidesurfaces 23 and 24 and also extend in a diagonal direction between upperportion 41 and lower portion 42. More particularly, connecting portions43 exhibit a forwardly-inclined configuration, but may also besubstantially vertical or rearwardly-inclined.

Upper portion 41, lower portion 42, and connecting portions 43collectively form a plurality of apertures that expose portions ofbladder 30. The apertures extend along side surfaces 23 and 24 in atleast heel region 17, and the shape of the apertures generally dependsupon the orientations of connecting portions 43 and the configurationsof upper portion 41 and lower portion 42. The apertures formed throughreinforcing element 40 are depicted as having the shape of aparallelogram, but may have a variety of shapes that include, forexample, oval, hexagon, triangle, circle, or various non-geometricshapes. The shape of the apertures may affect the compressioncharacteristics of reinforcing element 40 and may be selected,therefore, to provide particular properties to reinforcing element 40.

Reinforcing element 40 restricts the degree of outwardly-directedswelling in side surfaces 23 and 24, thereby retaining the intendedoverall shape of sole component 20. That is, the pressurized fluidwithin bladder 30 presses outward upon barrier layers 31 and 32, andreinforcing element 40 restrains the distension in side surfaces 23 and24 due to the pressure of the fluid. Portions of reinforcing element 40may, therefore, placed in tension by the pressurized fluid. Althoughupper portion 41 and lower portion 42 may experience such tension,connecting portions 43, which extend along side surfaces 23 and 24, maygenerally experience greater degrees of tension. Accordingly, connectingportions 43 may be placed in tension by the fluid pressure and operateto restrict the degree of outwardly-directed swelling or distension inside surfaces 23 and 24. As shown in FIG. 3 bladder 230 may haverecessed portions in side surfaces 23 and 24 to receive reinforcingelement 40 and allow closer contact between the bladder 30 andreinforcing element 40.

The specific configuration of reinforcing element 40 discussed above isintended to provide an understanding of reinforcing element 40 accordingto one configuration, and as depicted in FIGS. 2-7C. In furtherconfigurations, however, the configuration of reinforcing element 40 maybe significantly modified. For example, upper portion 41 may extend intoforefoot region 15, may extend over portions upper surface 21, or mayextend be absent from portions of regions 16 and 17. Similarly, lowerportion 42 may extend through each of regions 15-17, or lower portion 42may extend over portions of lower surface 22. The numbers and dimensionsof connecting portions 43 may also vary significantly. Accordingly,reinforcing element 40 may have a variety of configurations.

Reinforcing element 40 is recessed into bladder 30 such that anoutward-facing surface of reinforcing element 40 is generally flush withsurfaces 21-24 of bladder 30. Referring to FIGS. 7A-7C, theoutward-facing surfaces of connecting portion 43 are generally flushwith side surfaces 23 and 24. Accordingly, side surfaces 23 and 24 formrecesses that receive connecting portions 43. While the figures showsquared edges where contact is made with bladder 30, reinforcing element40 have beveled edges. Forming the various outward-facing surfaces ofreinforcing element 40 to be generally flush with surfaces 21-24 ofbladder 30 has an advantage of providing a smooth exterior configurationto sole component 20. In some configurations, however, theoutward-facing surfaces of reinforcing element 40 may be inset orrecessed into bladder 30 or may protrude outward beyond bladder 30.

A die-cutting process or molding process, for example, may be utilizedto form reinforcing element 40 from a diverse range of materials.Suitable materials for reinforcing element 40 include polyester,thermoset urethane, thermoplastic urethane, thermoplastic polyurethane,various nylon formulations, blends of these materials, or blends thatinclude glass fibers. In addition, reinforcing element 40 may be formedfrom a high flex modulus polyether block amide, such as PEBAX, which ismanufactured by the Atofina Company. Polyether block amide provides avariety of characteristics that benefit reinforcing element 40,including high impact resistance at low temperatures, few propertyvariations in the temperature range of minus 40 degrees Celsius topositive 80 degrees Celsius, resistance to degradation by a variety ofchemicals, and low hysteresis during alternative flexure. Anothersuitable material for reinforcing element 40 is a polybutyleneterephthalate, such as HYTREL, which is manufactured by E.I. duPont deNemours and Company. Composite materials may also be formed byincorporating glass fibers or carbon fibers into the polymer materialsdiscussed above in order to enhance the strength of reinforcing element40.

Although reinforcing element 40 may be formed from a single material,two or more materials may be incorporated into reinforcing element 40 insome configurations. One possibility is to make a laminate materialwhere there are different material layers. This would allow the insideportion of reinforcing element 40 (i.e., the portion adjacent to bladder30) to have one set of properties, and the outside portion ofreinforcing element 40 (i.e., the portion facing outward from footwear10) to have a different set of properties, depending on the materialschosen. For example, the inside portion of reinforcing element 40 couldhave a layer that facilitates bonding to bladder 30, and the outsideportion may be formed from a durable and wear-resistant material. Moreparticularly, the portion of reinforcing element 40 that contacts andbonds with bladder 30 may be formed from the same material as bladder 30to facilitate bonding, and the portion of reinforcing element 40 thatfaces away from bladder 30 may be formed from a different material.

The material forming reinforcing element 40 may exhibit a greatermodulus of elasticity than the material forming bladder 30. Whereas thematerial forming bladder 30 is generally flexible, the material formingreinforcing element 40 may exhibit semi-rigid or rigid properties.Comparisons between bladder 30 and reinforcing element 40 may alsorelate to the melting point and recrystalization temperatures. Asdiscussed in greater detail below, materials forming bladder 30 andreinforcing element 40 are joined through a molding process. Althoughthe melting point and recrystalization temperatures of bladder 30 andreinforcing element 40 may vary significantly, a difference in meltingpoints that is less than 35 degrees Celsius and a difference inrecrystalization temperatures that is at least 5 degrees Celsius may bebeneficial to the manufacturing process. In some configurations, theultimate tensile strength of the material forming bladder 30 may be lessthan the ultimate tensile strength of the material forming reinforcingelement 40.

Sole component 20, as described above, provides ground reaction forceattenuation as footwear 10 impacts the ground during running, walking,or other ambulatory activities. In addition, sole component 20 mayimpart stability or otherwise control foot motions, such as the degreeof pronation. The degree of ground reaction force attenuation providedby sole component 20, and the manner in which sole component 20 controlsfoot motions, are primarily determined by the configuration of bothbladder 30 and reinforcing element 40 and the properties of thematerials forming bladder 30 and reinforcing element 40. Accordingly,variations in the configuration of both bladder 30 and reinforcingelement 40, and the materials utilized therein, may be employed to tuneor otherwise control the ground reaction force attenuation and motioncontrol properties of sole structure 12.

As an additional matter, lower surface 22 forms an upwardly-beveled area25 in a rear-lateral portion of sole component 20 in order to permit thefootwear to smoothly roll both forward and to the medial side followingheel strike. As depicted in FIGS. 1 and 5, the vertical thicknesses ofthe portions of bladder 30 and reinforcing element 40 forming lateralside surface 23 decrease in rear portions of heel region 17. Therationale for the decreased thickness, which forms beveled area 25,corresponds with the typical motion of the foot during running, whichproceeds as follows: Initially, the heel strikes the ground, followed bythe ball of the foot. As the heel leaves the ground, the foot rollsforward so that the toes make contact, and finally the entire footleaves the ground to begin another cycle. During the time that the footis in contact with the ground and rolling forward, it also rolls fromthe outside or lateral side to the inside or medial side, a processcalled pronation. While the foot is air-borne and preparing for anothercycle, the opposite process, called supination, occurs. An advantage ofbeveled area 25 is to permit footwear 10 to smoothly transition from theposition at heel strike, wherein only the rear-lateral portion of solestructure 12 is in contact with the ground, to the position where asubstantial portion of outsole 14 is in contact with the ground. Thatis, beveled area 25 permits footwear 10 to smoothly roll both forwardand to the medial side following heel strike. Furthermore, the positionsof connecting portions 43 are selected such that a space is formedbetween two adjacent connecting portions 43 at the location of beveledarea 25. The space between adjacent connecting portions 43 furtherfacilitates a smooth transition from the position at heel strike byproviding greater compressibility to sole component 20 at the positionof beveled area 25.

Manufacturing Process For The Sole Component

One suitable manufacturing process for sole component 20 begins with theformation of the reinforcing element 40. Although a variety oftechniques may be utilized, reinforcing element 40 may be die-cut fromsheet stock, which enhances the efficiency of manufacturing footwear 10by eliminating the need for separate molds and molding operations. Moreparticularly, a sheet 51 that forms reinforcing element 40 may be placedbetween opposing portions of a die-cutting apparatus 50, as depicted inFIG. 8A. As apparatus 50 compresses sheet 51, as depicted in FIG. 8B,edges on a cutting surface 52 of apparatus 50 having the shape ofreinforcing element 40 may extend though and cut sheet 51. Following theopening of apparatus 50, as depicted in FIG. 8C, reinforcing element 40may be removed. Additional milling may be required to add beveled edgesor other modifications to the basic shape. Reinforcing element 40 maythen be cleansed with a detergent or alcohol, for example, in order toremove surface impurities, such as dust or fingerprints. The surface ofreinforcing element 40 may also be plasma treated to enhance bondingwith bladder 30.

Following the formation of reinforcing element 40, a mold is utilized toform bladder 30 and bond reinforcing element 40 to bladder 30. The moldincludes an upper mold portion 60 and a corresponding lower mold portion70, which are respectively depicted in FIGS. 9A and 9B. When joinedtogether, mold portions 60 and 70 form a cavity having dimensionssubstantially equal to the exterior dimensions of sole component 20. Themold may be utilized for thermoforming bladder 30 and simultaneouslybonding or otherwise securing reinforcing element 40 to the exterior ofbladder 30. In general, reinforcing element 40 is placed within uppermold portion 60 and two thermoplastic polymer sheets are placed betweenmold portions 60 and 70. The thermoplastic sheets are then drawn intothe contours of the mold such that at least one of the thermoplasticsheets contacts and is bonded to reinforcing element 40. In addition,mold portions 60 and 70 compress the thermoplastic sheets together toform peripheral bond 33. Once the thermoplastic sheets have conformed tothe shape of bladder 30, reinforcing element 40 is bonded to thethermoplastic sheets, peripheral bond 33 is formed, and bladder 30 maybe pressurized with a fluid and sealed, thereby forming sole component20.

Upper mold portion 60 is depicted individually in FIG. 9A and includes acavity 61 that forms the portions of sole component 20 correspondingwith upper surface 21 and side surfaces 23 and 24. A ridge 62 extendsaround cavity 61 and is partially responsible for forming peripheralbond 33. In addition, a plurality of protrusions 63 extend from asurface of cavity 61 and are partially responsible for forming interiorbonds 34. Accordingly, the area of upper mold portion 60 located withinthe area bounded by ridge 62 forms upper surface 21 and side surfaces 23and 24. An extension of ridge 62 extends outward from cavity 61 andforms an L-shaped channel 64. As discussed in greater detail below,channel 64 is utilized to form a conduit through which a fluid may beinjected into sole component 20. Another feature of upper mold portion60 is a plurality of slot vents 65 distributed throughout cavity 61.Vents 65 provide outlets for air as a thermoplastic sheet of polymermaterial is drawn into the contours of upper mold portion 60 during theformation of sole component 20.

Lower mold portion 70 is depicted individually in FIG. 9B and includes asurface 71 that forms the portion of sole component 20 correspondingwith lower surface 22. A ridge 72 extends around surface 71 and, incombination with ridge 62, is responsible for forming peripheral bond33. In addition, a plurality of protrusions 73 extend from surface 71and join with protrusions 63 to form interior bonds 34. Accordingly, thearea of lower mold portion 70 located within the area bounded by ridge72 forms lower surface 22. An extension of ridge 72 extends outward fromsurface 71 and forms an L-shaped channel 74. Channel 74 joins withchannel 64 to form the conduit through which the fluid may be injectedinto sole component 20. Another feature of lower mold portion 70 is aplurality of slot vents 75 distributed throughout surface 71. Vents 75provide outlets for air as a thermoplastic sheet of polymer material isdrawn into the contours of lower mold portion 70 during the formation ofsole component 20.

The manner in which the mold is utilized to form sole component 20 fromreinforcing element 40 and barrier layers 31 and 32 will now bediscussed. Initially, reinforcing element 40 is bent into a U-shape,placed between mold portions 60 and 70 and then positioned within uppermold portion 60, as depicted in FIGS. 10A and 10B, respectively. Uppermold portion 60 forms the portions of sole component 20 correspondingwith upper surface 21 and side surfaces 23 and 24. In the configurationof sole component 20 discussed above, reinforcing element 40 isgenerally bonded to side surfaces 23 and 24. Accordingly, positioningreinforcing element 40 within upper mold portion 60, as depicted in FIG.10B, properly positions reinforcing element 40 with respect to the moldfor the process of forming sole component 20. A variety of techniquesmay be utilized to secure reinforcing element 40 within upper moldportion 60, including a vacuum system, various seals, or non-permanentadhesive elements, for example.

Reinforcing element 40 may conduct heat from the mold, thereby raisingthe temperature of reinforcing element 40. In some configurations,reinforcing element 40 may be heated prior to placement within the moldin order to decrease manufacturing times. Radiant heaters may also beutilized to heat surfaces of reinforcing element 40 while located withinthe mold. Following placement of reinforcing element 40 within uppermold portion 60, a pair of thermoplastic polymer sheets that formbarrier layers 31 and 32 are heated and then positioned between moldportions 60 and 70, as depicted in FIG. 10C. The temperatures to whichreinforcing element 40 and barrier layers 31 and 32 are heated dependsupon the specific material used.

Once barrier layers 31 and 32 are positioned, mold portions 60 and 70are then located such that ridge 62 aligns with ridge 72 and the variousprotrusions 63 are aligned with protrusions 73. In this position, theareas of mold portions 60 and 70 that form corresponding portions ofsole component 20 are positioned on opposite sides of barrier layers 31and 32 and are also aligned. Mold portions 60 and 70 then translatetoward each other such that the mold contacts and compresses barrierlayers 31 and 32, as depicted in FIG. 10D.

As the mold contacts and compresses portions of barrier layers 31 and32, a fluid, such as air, having a positive pressure in comparison withambient air may be injected between barrier layers 31 and 32 to inducebarrier layers 31 and 32 to respectively contact and conform to thecontours of mold portions 60 and 70. A variety of methods may beemployed to pressurize the area between barrier layers 31 and 32. Forexample, the fluid may be directed through the conduit formed bychannels 64 and 74. Air may also be removed from the area betweenbarrier layers 31 and 32 and mold portions 60 and 70 through vents 65and 75, thereby drawing barrier layers 31 and 32 onto the surfaces ofmold portions 60 and 70. In addition, drawing barrier layers 31 and 32onto the surfaces of mold portions 60 and 70 also draws barrier layers31 and 32 into contact with reinforcing element 40. Accordingly, barrierlayers 31 and 32 contact and are bonded to reinforcing element 40 duringthis portion of the manufacturing process.

As the area between barrier layers 31 and 32 is pressurized and air isremoved from the area between barrier layers 31 and 32 and mold portions60 and 70, barrier layers 31 and 32 conform to the shape of the mold andare bonded together. More specifically, barrier layers 31 and 32stretch, bend, or otherwise conform to extend along the surfaces ofcavity 61 and surface 71 and form the general shape of bladder 30. Ridge62 and ridge 72 also compress a linear area of barrier layers 31 and 32to form peripheral bond 33. In addition, barrier layers 31 and 32conform to the shapes of protrusions 63 and 73 and are bonded togetherby being compressed between protrusions 63 and 73, thereby forminginterior bonds 34.

Although barrier layers 31 and 32 conform to extend along the contoursof cavity 81 and surface 71, upper barrier layer 31 generally does notcontact the portions of cavity 61 that are covered by reinforcingelement 40. Rather, upper barrier layer 31 contacts and is compressedagainst the inward-facing surface of reinforcing element 40, therebybonding upper barrier layer 31 to reinforcing element 40. As barrierlayers 31 and 32 conform to the shape of the mold and are bondedtogether, upper barrier layer 31 bends at the location of upper portion41 to form side surfaces 23 and 24. That is, upper barrier layer 31extends in a generally horizontal direction to form upper surface 21,and upper barrier layer 31 bends at the location of upper portion 41 toextend in a generally vertical direction and form side surfaces 23 and24. Accordingly, upper barrier layer 31 bends during the process ofmolding bladder 30 in order to form upper surface 21 and side surfaces23 and 24.

The thickness of upper barrier layer 31 prior to molding may be greaterthan the thickness of lower barrier layer 32. Although barrier layers 31and 32 may exhibit different thicknesses prior to molding, each ofbarrier layers 31 and 32 may have a substantially uniform thicknessfollowing molding. Whereas lower barrier layer 32 only forms lowersurface 22, upper barrier layer 31 forms both upper surface 21 and sidesurfaces 23 and 24. The rationale for the difference in thickness isthat upper barrier layer 31 may stretch to a greater degree in order toform both upper surface 21 and side surfaces 23 and 24. Accordingly,differences between the original, pre-stretched thicknesses of barrierlayers 31 and 32 compensate for thinning in upper barrier layer 31 thatmay occur when upper barrier layer 31 is stretched or otherwisedistorted during the formation of upper surface 21 and side surfaces 23and 24.

The various outward-facing surfaces of reinforcing element 40 aregenerally flush with some portion of surfaces 21-24 of bladder 30. Asair pressurizes the area between barrier layers 31 and 32 and air isdrawn out of the mold through vents 65 and 75, both upper barrier layer31 and reinforcing element 40 are compressed against the surface ofcavity 61. Upper barrier layer 31 contacts the inward-facing surface ofreinforcing element 40, conforms to the shape of reinforcing element 40,extends around reinforcing element 40, and contacts the surface ofcavity 61. In this manner, the surfaces of reinforcing element 40 areformed to be generally flush with surfaces 21-24 of bladder 30.

Once sole component 20 is formed within the mold, mold portions 60 and70 separate such that reinforcing element 40 and barrier layers 31 and32 may be removed from the mold, as depicted in FIG. 11. The polymermaterials forming reinforcing element 40 and barrier layers 31 and 32are then permitted to cool and a pressurized fluid may be injectedthrough the conduit formed by channels 64 and 74. The conduit is thensealed to enclose the fluid within bladder 30. In addition, excessportions of barrier layers 31 and 32 may be trimmed or otherwise removedfrom sole component 20. The excess portions may them be recycled orreutilized to form additional thermoplastic sheets.

Following the formation of sole component 20, upper 11 may be secured toupper surface 21 and outsole 14 may be secured to lower surface 22,thereby substantially completing the manufacture of footwear 10. Theprocess of bonding outsole 14 to lower surface 22 may be performedfollowing the formation of sole component 20, as discussed above.Alternately, one or more traction elements may be located within themold in order to form a bond between the traction elements and lowersurface 22 during the thermoforming process. That is, the tractionelements may be bonded to bladder 30 through a process that is similarto the process of bonding reinforcing element 40 to bladder 30. Thetraction elements may be one or more elements of rubber material, forexample, that are similar in configuration to a conventional outsole.The traction elements may also be additional elements of thermoplasticmaterial that reinforce those areas of sole component 20 that contactthe ground. Accordingly, the traction elements may have a variety ofconfigurations.

Although thermoforming is a suitable manner of forming sole component20, a blow-molding process may also be utilized. In general, a suitableblow-molding process involves positioning reinforcing element 40 withinat least one of two mold portions and then positioning a parison betweenthe mold portions. The parison is a generally hollow and tubularstructure of molten polymer material. In forming the parison, the moltenpolymer material is extruded from a die. The wall thickness of theparison may be substantially constant, or may vary around the perimeterof the parison. Accordingly, a cross-sectional view of the parison mayexhibit areas of differing wall thickness. Suitable materials for theparison include the materials discussed above with respect to bladder30. Following placement of the parison between the mold portions, themold portions close upon the parison and pressurized air within theparison induces the liquefied elastomeric material to contact thesurfaces of the mold. In addition, closing of the mold portions and theintroduction of pressurized air induces the liquefied elastomericmaterial to contact the surfaces of reinforcing element 40. Air may alsobe evacuated from the area between the parison and the mold to furtherfacilitate molding and bonding. Accordingly, sole component 20 may alsobe formed through a blow molding process wherein reinforcing element 40is placed within the mold prior to the introduction of the moltenpolymer material.

A variety of other manufacturing techniques may also be utilized to formsole component 20, in addition to thermoforming and blow-molding. Forexample, bladder 30 may be formed separate from reinforcing element 40,and both components may be subsequently bonded together. Adual-injection technique may also be utilized to simultaneously formbladder 30 and reinforcing element 40 from separate materials. In someconfigurations, a first element corresponding with upper surface 21 andside surfaces 23 and 24 may be formed, a second element correspondingwith lower surface 22 may be joined thereto, and a third elementcorresponding with reinforcing element 40 may then be secured to theexterior. Accordingly, structures having the general shape and featuresof sole component 20 may be formed from a variety of processes.

Additional Configurations Of The Sole Component

The specific configuration of sole component 20 disclosed above isintended to provide an example of a suitable structure for a solecomponent. In further configurations, either of bladder 30 orreinforcing element 40 may exhibit various alternate configurations. Asan example, bladder 30 may be structured to have two or moresubchambers. Whereas bladder 30 is disclosed above as being a singlechamber that extends along the entire length of footwear 10, bladder 30may have various subchambers that are pressurized differently andisolated from fluid communication with each other. Another configurationis possible wherein bladder 30 includes various indentions ordepressions that receive side portions of outsole 14 and permit the sideportions of outsole 14 to wrap upward and onto one or both of sidesurfaces 23 and 24. An advantage of having outsole 14 wrap upward andonto one or both of side surfaces 23 and 24 is that outsole 14 protectsside surfaces 23 and 24 from contacting the ground and incurring damage.Outsole 14 may not be flush in all configurations of sole component 20.

Reinforcing element 40 may also exhibit various alternateconfigurations. As an example, reinforcing element 40 may form bridgesthat extend across upper surface 21 and between medial and lateral sidesof upper portion 41 to enhance the stability of sole component 20. Aswith other portions of reinforcing element 40, the bridges may berecessed within indentations in bladder 30 and may be bonded to bladder30 during the thermoforming process. Bridges may also extend acrosslower surface 22 or across both of surfaces 21 and 22 in any of regions15-17. Reinforcing element 40 may also form extensions that extendupward from sole component 20 to interface with areas of upper 11. Moreparticularly, the extensions may extend upward from reinforcing element40 to join with upper 11. In further configurations, a portion ofreinforcing element 40 may extend upward to form a heel counter, orportions of reinforcing element 40 may extend upward to form lacingmembers. Another configuration is that reinforcing element 40 may beformed from two or more materials. For example, upper portion 41 may beformed from a first material, while lower portion 42 and connectingportions 43 may be formed from a second material. The first material mayexhibit lesser stiffness than the second material. This configurationprovides a softer material adjacent to upper 11, which may enhance thecomfort of footwear 10 and promote bonding between sole structure 12 andupper 11. Also, the dimensions of reinforcing element 40 may be modifiedto change the compressibility, stability, flexibility, reaction forceattenuation properties, and the torsional resistance of sole component20.

Sole component 20 may also include a supplemental layer that extendsover lower surface 22. Modifying the thickness and placement of thesupplemental layer may impart specific properties as regards stability,compression, and puncture resistance to sole component 20 and allowdifferent configurations of sole component 20 for different needs oractivities. As an alternative to the supplemental layer or in additionto the supplemental layer, outsole 14 may be structured to control thedegree to which surfaces of sole component 20 compress or otherwisedeform.

The stability and compressibility properties of sole component 20 may bemodified by altering the configuration of interior bonds 34. In contrastwith the generally horizontal configuration of interior bonds 34depicted in FIGS. 7A-7C, alternate configurations of the bonds could beinclined or otherwise sloped. For example, interior bonds 34 can beoriented to form a downward incline extending away from each of sidesurfaces 23 and 24. In this configuration, the stretch in upper barrierlayer 31 during the thermoforming process is lessened adjacent to sidesurfaces 23 and 24. Another example involves decreasing an elevation ofinterior bonds 34 in a central area of sole component 20. In this form,the stretch in upper barrier layer 31 is increased in the central areadue to the configuration of interior bonds 34. The increased stretch inthis area provides upper barrier layer 31 with lesser thickness, therebyincreasing the compressibility of upper barrier layer 31 in the centralarea.

The configuration of reinforcing element 40 depicted in FIGS. 7A and 7Bis formed from a single layer of material. As discussed above, however,reinforcing element 40 may be formed from multiple layers, includingvarious laminate materials. As an example, which is depicted in FIG.12A, reinforcing element 40 may be a laminate formed from two layers ofequal thickness. Different thickness ratios may also be used. Forexample, FIG. 12B depicts a layered configuration wherein each of thelayers have a different thickness. More particularly, a thickness of theinterior layer is approximately one-half a thickness of the exteriorlayer. Other thickness ratios or even additional layers within thelaminate are also possible.

An advantage to forming reinforcing element 40 with a layeredconfiguration may be to impart different properties to the inside andoutside of reinforcing element 40. For example, the interior layer maybe formed from a material that readily bonds to bladder 30, and theexterior layer may be formed from a material that resists wear orimparts greater stability to sole component 20. In some configurations,the interior layer may be formed from the same material as bladder 30.When, for example, the interior layer of reinforcing element 40 andbladder 30 are both formed from the same thermoplastic polymer material,then the bonding affinity between reinforcing element 40 and bladder 30may be increased. As another example, the exterior layer may be formedfrom a material (e.g., a metal or a textured or colored polymer) thatimparts a particular aesthetic aspect to footwear 10, whereas theinterior layer may be a material that bonds with bladder 30.Accordingly, forming reinforcing element 40 to have a layeredconfiguration may be utilized to impart the properties of two differentmaterials to sole component 20.

Additionally, other portions of reinforcing element 40 may be made fromdiffering materials. For example, as shown in FIG. 12C, upper portion 41may be formed from a material that exhibits lesser stiffness than amaterial forming lower portion 42. This configuration provides a softermaterial adjacent to upper 11, which may enhance the comfort of footwear10 and promote bonding between sole structure 12 and upper 11. Inaddition, some configurations may vary the materials throughoutreinforcing element 40 in order to provide specific compression,stability, and flexibility properties to particular portions ofreinforcing element 40. An example is shown in FIG. 12D, wherein amedial side of reinforcing element 40 is formed from a differentmaterial than a lateral side of reinforcing element 40. An advantage tostructuring sole component 20 to exhibit lesser medial compressibilitymay be to reduce the degree of pronation in the foot. Accordingly,forming reinforcing element 40 from different materials in various areasmay be utilized to impart different properties to the various areas.

The compressibility of peripheral areas of sole component 20 may beselected through modifications in the overall thickness of reinforcingelement 40. As depicted in FIG. 12E, the thickness of reinforcingelement 40 may be tapered between upper portion 41 and lower portion 42in order to control the compressibility of reinforcing element 40 orlimit the degree to which reinforcing element 40 creases or bucklesduring compression. In addition, a central area of reinforcing element40 may exhibit a greater thickness than portions 41 and 42 in order toimpart a specific compressibility, as shown in FIG. 12F.

In the configuration discussed above, reinforcing element 40 extendsfrom heel region 17 to approximately midfoot region 16 on both thelateral and medial sides of sole structure 20. However, reinforcingelement 40 may extend through all of regions 15-17 or may be restrictedto one or more of the regions 15-17. FIG. 13A depicts a configuration ofreinforcing element 40 that is limited only to the heel region 17.Alternately, FIG. 13B depicts a configuration of reinforcing element 40that extends through each of regions 15-17.

Reinforcing element 40 is depicted above as having relatively largeapertures with an approximate parallelogram shape. However, the size andshape of the apertures is not limited to this configuration and may beround, oval or other geometric or non-geometric shapes. FIGS. 13C-13Hdepict several possible aperture shapes, including triangular as in FIG.13C, hexagonal as in FIG. 13D, circular as in FIG. 13E, or slit-shapedas in FIG. 13F. However, possible shapes are not limited to these andmay be other geometric or non-geometric shapes. Additionally, theapertures themselves may be of any size from relatively large, asdepicted in FIGS. 1-6, to relatively small, as in FIG. 13G. Reinforcingelement 40 may also have a mixture of aperture sizes, as shown in FIG.13H. In other configurations, a mixture of aperture sizes and shapes maybe used, as in FIG. 131. In some configurations, apertures may be absentfrom reinforcing element 40, as depicted in FIG. 13J.

The edges of reinforcing element 40, as depicted in FIG. 7A and 7B,exhibit a squared cross section. In order to facilitate closer contactbetween reinforcing element 40 and bladder 30, some or all of the edgesof reinforcing element 40 may be beveled, as depicted in FIG. 14. Thismay minimize stretch and potential thinning in areas where upper barrierlayer 31 contacts reinforcing element 40 during the manufacturingprocess.

Conclusion

The preceding discussion disclosed various sole component configurationsand a methods of manufacturing the sole components. In general, the solecomponents include a fluid-filled bladder and a reinforcing elementextending around the bladder. The reinforcing element is bonded to theexterior of the bladder, and may be recessed into the bladder. In someconfigurations, the reinforcing element extends along the side surfacesof the bladder and between upper and lower surfaces of bladder. Inmanufacturing the sole component, the reinforcing element may be locatedwithin a mold, and the polymer material forming the bladder may bebonded to the reinforcing element during the molding process.

The present invention is disclosed above and in the accompanyingdrawings with reference to a variety of configurations. The purposeserved by the disclosure, however, is to provide an example of thevarious features and concepts related to the invention, not to limit thescope of the invention. One skilled in the relevant art will recognizethat numerous variations and modifications may be made to theconfigurations described above without departing from the scope of thepresent invention, as defined by the appended claims.

1-13. (canceled)
 14. A sole structure for an article of footwear havingan upper, a forefoot region, a midfoot region, and a heel region, thesole structure comprising: a chamber enclosing a fluid and including anupper surface opposing the upper and a side surface depending from theupper surface; and a reinforcing element (i) attached to the chamber atthe side surface, (ii) extending continuously from a first endterminating at a medial side of the midfoot region, around the heelregion, to a second end terminating at a lateral side of the midfootregion, and (iii) including at least one aperture, the chamber extendingthrough the at least one aperture and having an arcuate surface thatforms an outer surface of the sole structure.
 15. The sole structure ofclaim 14, wherein the reinforcing element includes a first portionattached to the side surface of the chamber and having a first stiffnessand a second portion attached to the side surface of the chamber andhaving a second stiffness different than the first stiffness.
 16. Thesole structure of claim 15, wherein the first portion and the secondportion are arranged in a stacked configuration continuously from thefirst end to the second end with the second portion being disposedbetween the first portion and the upper.
 17. The sole structure of claim16, wherein the first portion is substantially flush with the secondportion.
 18. The sole structure of claim 16, wherein the first portionabuts the second portion.
 19. The sole structure of claim 16, whereinthe first portion is formed from a different material than the secondportion.
 20. The sole structure of claim 16, wherein the first portionincludes a greater stiffness than the second portion.
 21. The solestructure of claim 16, wherein the first portion includes a first outersurface and the second portion includes a second outer surface, thefirst outer surface cooperating with the second outer surface of thesecond portion and the arcuate surface of the chamber to form an outersurface of the sole structure.
 22. The sole structure of claim 14,wherein the at least one aperture is one of (i) a polygon, (ii) acircle, or (iii) elongate.
 23. An article of footwear incorporating thesole structure of claim
 14. 24. A sole structure for an article offootwear having an upper, a forefoot region, a midfoot region, and aheel region, the sole structure comprising: a chamber enclosing a fluidand including an upper surface opposing the upper and a side surfacedepending from the upper surface; and a reinforcing element (i) attachedto the chamber at the side surface, (ii) extending continuously from afirst end terminating at a medial side of the midfoot region, around theheel region, to a second end terminating at a lateral side of themidfoot region, and (iii) including a first portion, a second portion,and at least one aperture formed through at least one of the firstportion and the second portion, at least one of the first portion andthe second portion received by a recessed portion of the chamber at theside surface.
 25. The sole structure of claim 24, wherein the chamberextends through the at least one aperture and includes an arcuatesurface that forms an outer surface of the sole structure.
 26. The solestructure of claim 25, wherein the first portion includes a first outersurface and the second portion includes a second outer surface, thefirst outer surface cooperating with the second outer surface of thesecond portion and the arcuate surface of the chamber to form an outersurface of the sole structure.
 27. The sole structure of claim 24,wherein the first portion and the second portion are arranged in astacked configuration continuously from the first end to the second endwith the second portion being disposed between the first portion and theupper.
 28. The sole structure of claim 27, wherein the first portion issubstantially flush with the second portion.
 29. The sole structure ofclaim 27, wherein the first portion abuts the second portion.
 30. Thesole structure of claim 27, wherein the first portion is formed from adifferent material than the second portion.
 31. The sole structure ofclaim 27, wherein the first portion includes a greater stiffness thanthe second portion.
 32. The sole structure of claim 24, wherein the atleast one aperture is one of (i) a polygon, (ii) a circle, or (iii)elongate.
 33. An article of footwear incorporating the sole structure ofclaim 24.